Recently, there has been a test proposed for determining the presence/absence of a suspected substance in blood by using a test kit including a sample liquid preparing apparatus and a test cartridge. A conventional sample liquid preparing apparatus collects, for example, whole blood as a sample from the human body. Upon external application of a predetermined force, the sample liquid preparing apparatus injects a predetermined amount of sample process liquid stored inside the unit into a test cartridge while mixing it with a collected sample. The test cartridge includes a filter in which a first reagent has been adsorbed, which reacts with a liquid mixture of a sample process liquid and a sample and a strip into which a second reagent has been adsorbed, which reacts with the reaction liquid which has reacted with the liquid mixture and the first reagent. When the liquid mixture is injected into the test cartridge, the liquid mixture passes through the filter provided in the test cartridge. With this operation, the first reagent elutes into the liquid mixture. The reaction liquid which has reacted with the liquid mixture and the first reagent moves on the strip by a capillary action. With this operation, the second reagent elutes into the reaction liquid.
In the above arrangement, however, the concentration of a sample contained in a liquid mixture injected from the sample liquid preparing apparatus is not consistent between the early and final phases of injection. That is, since a large amount of sample elutes into the sample process liquid in the early phase of injection, the concentration of the sample is high in the early phase of injection and gradually decreases toward the final phase. In addition, in the test cartridge, the amount of first reagent eluting into the liquid mixture is large in the early phase in which the liquid mixture passes through the filter, and gradually decreases toward the final phase of the passage. When the liquid mixture is not uniformly mixed and the first reagent does not uniformly elute into the liquid mixture as described above, a correct test result may not be obtained.